1. Field
The present invention generally relates to a fixing apparatus, and particularly relates to a fixing apparatus having a retention module and a back plate engaged with the retention module so that the retention module and the back plate are both secured on a printed circuit board whereby a heat sink attached to the retention module can be securely mounted on the printed circuit board.
2. Related Art
With advancement of computer technology, electronic devices operate with high speeds. It is well known that the more rapidly the electronic devices operate, the more heat they generate. If the heat is not dissipated duly, the stability of the operation of the electronic devices will be impacted severely.
Generally, in order to ensure the electronic device to run normally, a heat sink is used to dissipate the heat generated by the electronic device. And in order to facilitate installation of the heat sink to the electronic device, a retention module is employed. Commonly, the retention module is mounted onto a printed circuit board and is around the electronic device. One the other hand, to enhance the strength of the printed circuit board, a back plate is applied underneath the printed circuit board. An example of a combination comprising a retention module and a back plate both secured to a printed circuit board, is taught in U.S. Pat. No. 6,549,412B1. In this patent, the retention module forms four downward posts adjacent four corners thereof. A heat sink (not shown) is to be fixed to the retention module. Each post defines a through hole therein. The back plate comprises four poles corresponding to the through holes of the retention module. In assembly, the poles extend through the printed circuit board and the through holes of the retention module, and further protrude from a top surface of the retention module. The protruded portions of the poles are stamped to thereby form rivet joints between the retention module and the back plate. Thus, the retention module and the back plate are attached on opposite sides of the printed circuit board, whereby the heat sink fixed on the retention module is secured to the printed circuit board to thermally contact with a CPU (not shown) mounted on the printed circuit board and surrounded by the retention module.
Free ends of the poles of the '412 patent are stamped after the retention module and the back plate are placed to the printed circuit board. That is to say, the printed circuit board is placed in a situation subjected to stamping procedure, with the retention module and the back plate. The printed circuit board is thus at the risk of being damaged under stamping force or huge vibration during stamping the poles. Additionally, stamping the free ends of the poles increases the assembly cost.
It is strongly desired to provide an improved heat sink fixing apparatus which overcomes the above problem.